Resistive memory devices with an insulating film sandwiched between the electrodes can meet the needs of high-performance, high-density memories with low power requirements for data storage. Recently Scientists have developed a memory device with excellent switching properties and low power consumption for data storage applications They are devices with resistive switching characteristics, which refer to physical phenomena in which a dielectric (an electrical insulator that can be polarized by an applied electric current) suddenly changes its (double-ended) resistance when a strong current is applied.
Although these devices have been intensively studied to meet the enormous technological demands in terms of performance, several technical issues still remain, posing major challenges to their commercialization. Scientists are making extensive efforts to design resistive switching memory devices that are nonvolatile, reliable, and perform much better than existing silicon-based flash memory technologies.
Mrs. Swathi S.P. and Dr. S. Angappane of Center for Nano and Soft Matter Sciences (CeNS), Bangalore, an autonomous institution of the Ministry of Science and Technology, Govt. of India (DST), have developed a low-power memory device with excellent switching properties made from the chemical hafnium oxide, a substitute for silicon oxide, for data storage applications.
As an insulating layer, they used hafnium oxide (HfO2), an insulator that can be polarized by applying an electric current. They prepared by a method called the sputtering method. It is a physical vapor deposition technique in which energetic ions are used to bounce atoms or molecules from a desired “target” material and deposit them on a substrate. The resistive switching characteristics of the HfO2 film can be further improved by tuning the growth temperature and annealing conditions – a heat treatment process that changes the physical and sometimes chemical properties of the material to increase ductility and decrease hardness to make it more processable.
The team found that a higher concentration of oxygen vacancies (the loss of oxygen from their respective positions in the crystal lattice) is created when these films are subjected to a thermal heat treatment process called annealing. Oxygen vacancies play a critical role in creating the conditions for low power operation. In addition, the heat treatment also affected the crystalline behavior and defect density of the hafnium oxide films, thereby affecting the resistive switching parameters and device performance. In addition, the devices also showed good durability and high retention.
Their research, published in the Journal of Alloys and Compounds, may contribute to the development of more efficient, viable and reliable resistive memory devices in the future. CeNS researchers are converting these resistive memory devices into miniature forms. The team is exploring brain-inspired functions in these memory devices and exploring the possibility of integrating the memory device with other potential sensors to take advantage of its multi-functional capabilities.
For more read: 10.1016/j.jallcom.2022.165251